Genetic structure of Galdieria populations from Iceland

Galdieria is a photosynthetic unicellular protist, inhabiting thermoacidic environments around the world. The synchronicity of these thermoacidophilic algae with their extreme habitats makes them unable to thrive in different ecological conditions. The genetic structure of Galdieria populations has not yet been studied. In this report, the level of genetic diversity and struc- ture of five Galdieria populations from Iceland were assessed through both random amplified polymorphic DNA (RAPD) markers, and a partial calmodulin gene fragment (previously used to assess the population structure of these extremophilic algae). The level of population differentiation from both the RAPD and CaM markers was estimated using PLP, percentage of polymorphic loci; H, the expected heterozygosity; I, Shannon’s information index, Ks, Kst. The migration ability of the Galdieria populations was suggested by the high level of genetic variations scored within each Galdieria population and by the small number of polymorphisms detected between the different Icelandic populations. The low genetic diversity between the two species was highlighted by RAPD and calmodulin markers, suggesting for the first time an interspecific genetic flow between species as strategy to evolve in stressful environments.